Machines used to wrap and seal articles and packages in thermoplastic film are well known in the art. Two types of machines are commonly referred to as side-sealing and lap-sealing machines. In the typical side-sealing configuration, an article or set of articles travels, typically via a conveyer belt, toward the machine. A sheet of center-folded plastic film, having two layers, is fed from a direction which is preferably perpendicular to the direction of the conveyer. The two layers of the film are then separated such that the article is placed between the lower layer and the upper layer. On one side of the article is the center-fold, while on the other side, there is an open edge where the two layers are not attached. The machine has a side sealing mechanism, which typically comprises several sets of belts to hold and guide the film, a heating/sealing element that fuses or welds the two layers together and a cutting element that removes the excess material. Thus, as the article passes by the side sealing mechanism, this open edge is sealed by welding the two layers together, the plastic is cut and the waste is removed and discarded. At this point, the plastic film resembles a tube, with openings at both the leading and trailing ends of the article, but sealed along both sides. As the article continues to advance, an end sealing mechanism is then employed to seal the film at the leading end of the article. The article is then advanced and the end sealing mechanism then seals the film at the trailing end of the article.
Incomplete, inconsistent or sloppy welds can be problematic with these types of machines. One specific issue is caused by the temperature and sharpness of the cutting element. If the temperature is too low, or the cutting surface becomes dull, the ability to create a high quality seal is reduced. Thus, to maintain a satisfactory output, it is necessary to replace the cutting element when it wears. In machines of the prior art, the cutting element is typically a single blade, typically with a cutting surface having a radius. Once this blade wears or becomes covered with film, it must be replaced. Replacement of the cutting element requires removal of the used blade and the insertion of a new blade.
The cost associated with replacement blades can be significant. Also, it is imperative that a supply of replacement blades be available, since the sealing machine is completely inoperative without a blade.